Supply voltage

the 460 V rms 3 phase full wave controlled rectifier feeds an inductive charge. The supply voltage has a frequency of 50 Hz. If transistors are considered ideal;

a. draw the voltage seen on the load when a= 25.

b. draw the voltage seen on the load while the FWD diode is parallel to the load when a = 15 .

c. draw the voltage seen on the load when a = 75°.

d. a = 90 when there is a parallel FWD d